To provide a personal authentication system that enables a client to receive services even if he fails to carry his card or the like with him or loses it, thus preventing the abuse of the card or the like by a third person and the leakage of the personal information. When data identifying a client are transferred to an authentication server using an authentication terminal, the authentication server collates the sent data against personal authentication data registered previously in a database to identify the client and sends the results of the identification to the authentication terminal. After the authentication, when the authentication terminal requests the payment of charges from a settling account registered previously in the database, the read and modification of personal data, or the like, the authentication server executes a process based on the sent request.